up and placing the black bag with the explosive device in it, and because of the video enhancement technology, mostly dprept sto from the department store, they clearly identified a suspect, a single suspect and an arrest has been made. a briefing scheduled for later this evening, obviously. >> so let's reset chronologically. do we know what point they wound up identifying somebody, do we know a time window? >> i can tell you i was on just before 10:00 last night with anderson cooper and an hour or so before that i talked to a boston source who said we're stymied at the moment. we're doing a great job with the forensics. we know how the bombs work. we know about their power. we have a very good idea of the timing obviously because of all of the video. the who part, this source said they were stymied, so clearly from yesterday evening to the overnight hours, in analyzing this additional video, they were all day yesterday canvassing through the neighborhood, it is a holiday, the stores were closed and on monday when this took place. they go in and say what do you got, and looking at reams of ev